Fine root dynamics with stand development in the boreal forest

Abstract

Summary1. Despite greater importance of below ground in influencing terrestrial carbon and nutrient cycling than above ground, how below-ground biomass, production, turnover and mortality change with stand development remains poorly understood. 2. Here, we used a postfire boreal forest chronosequence that spanned over 200 years (3, 11, 29, 94, 142 and 205 years since fire) to study how the dynamics of fine roots ( 2 mm in diameter) vary with stand age. We collected 756 sequential cores and 270 ingrowth cores, each separated to layers and live/dead, resulting in a total of 5076 fine root samples to quantify fine root biomass, production, mortality and turnover rates. 3. With stand development, fine root biomass increased from 3 to 94-year-old, and declined thereafter, whereas necromass increased to 142-year-old and levelled off at 205-year-old. Fine root production and turnover increased from 3 to 11-year-old stands, and declined thereafter. Fine root mortality increased from 3 to 142-year-old stands. 4. Our study, the first to show four simultaneous stand age-dependent below-ground attributes, indicated that fine roots in young stands turn over faster than in old stands based on the estimates from both sequential and ingrowth cores. Despite some similarities among the studied attributes, the peaks they reached were not the same. Our results suggest that fine root dynamics are influenced by changes in species composition and soil properties associated with stand development in the boreal forest, especially the increase in forest floor nitrogen: phosphorus ratios as stand age increases.

Effect of Stand Age on Fine Root Biomass, Production and Morphology in Chinese Fir Plantations in Subtropical China

“…These results were consistent with some of the reported surveys. For instance, Yuan and Chen [44] revealed that in boreal forest fine root production increased initially to a peak, and declined thereafter, although other studies showed positive [32], negative stand age effects [45] or no effects on fine root production and turnover rate [46].…”

Carbon budgets in fertile silver birch (Betula pendula Roth) chronosequence stands

“…(Nadelhoffer and Raich, 1992;Eissenstat and Yanai, 1997;Jackson et al, 2000;Makkonen and Helmisaari, 2001;Block et al, 2006;Jones et al, 2009;Hodge et al, 2009;Rosenvald et al, 2011;Finér et al, 2011;Yuan and Chen, 2012).…”

Effects of salt stress on eco-physiological characteristics in Robinia pseudoacacia based on salt-soil rhizosphere

“…that control fine root dynamics are still poorly understood (Yuan and Chen, 2012). Moreover, roots play an important role on soil microbial community and enzyme activity (Xiao et al, 2015) and soil improvement.…”

“…A large number of studies have attempted to explain this decline by photosynthetic physiology and the effects of stand age on soil nutrient availability, on biomass allocation, and on stand structure (Mao et al, 2011). However, how below-ground biomass dynamics with stand development is not clear at present (Ryan et al, 1997;Yuan and Chen, 2012).…”